CN215888203U

CN215888203U - Post-grouting miniature steel pipe pile structure

Info

Publication number: CN215888203U
Application number: CN202122235235.7U
Authority: CN
Inventors: 占旭栋; 杨彦鑫; 贾万帅; 张垒; 程峰
Original assignee: Guilin University of Electronic Technology
Current assignee: Guilin University of Electronic Technology
Priority date: 2021-09-15
Filing date: 2021-09-15
Publication date: 2022-02-22
Anticipated expiration: 2031-09-15

Abstract

The utility model discloses a post-grouting miniature steel pipe pile structure which comprises a miniature steel pipe vertically arranged in a pile hole, wherein a steel bar is vertically arranged in the miniature steel pipe to the bottom of the pile hole, a bearing plate is arranged at the top of the miniature steel pipe, cement slurry is filled in the miniature steel pipe to form a cement column to the top of the miniature steel pipe, so that the miniature steel pipe, the steel bar and the bearing plate are connected into a whole, and the outer circular surface of the upper part of the miniature steel pipe is filled with the cement slurry to form a special-shaped cement column. The structure has the characteristics of simple construction, strong site adaptability, small disturbance to the construction surrounding environment, high bearing capacity and the like, overcomes the defects in the prior micro-pile technology, and improves the economy of the micro-steel pipe pile in the karst area.

Description

Post-grouting miniature steel pipe pile structure

Technical Field

The utility model relates to the technical field of pile foundation reinforcement foundation in the field of foundation treatment, in particular to a post-grouting miniature steel pipe pile structure.

Background

The first few Fernando Lizzi Italy proposed micro-piles of which the pile form was cast in steel reinforcement and cement mortar to increase the bearing capacity of the pile foundation by fully exerting the side frictional resistance of the pile. Compared with the traditional pile, the pile diameter of the micro pile is generally less than 0.3m, the length-diameter ratio (the ratio of the length to the diameter) is generally greater than 30.0, and the pile body is generally composed of cement paste and reinforcing steel bars.

In 1980, the micro-pile is introduced and applied to the protection of the lookout tower beside the shield engineering, and then the micro-pile is widely applied to the practical engineering abroad. The micro-pile is introduced in 1980 in China, corresponding indoor mechanical tests are developed by Tongji university, and then the micro-pile is used in projects such as building reconstruction and reinforcement, composite foundation, landslide control, foundation pit support, roadbed slope reinforcement and the like in China.

In karst areas, geological conditions are variable, geotechnical engineering conditions of building site foundations are complex, and arrangement of long piles is limited due to the existence of karst caves. Therefore, the influence of potential unfavorable geology on the building safety needs to be taken into consideration, uncertainty caused by unfavorable geological conditions such as karst caves and the like needs to be avoided as much as possible when the bearing capacity of the foundation is improved, and a micro pile structure and a construction method which can effectively treat the foundation in a karst area and have the characteristics of simplicity in construction, strong site adaptability, small disturbance to the surrounding construction environment, high bearing capacity and the like are urgently needed to be found.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the problems of uneven settlement of the ground surface, increased settlement of the ground surface, reduced bearing capacity of foundation soil and the like caused by poor geological types, provide a post-grouting miniature steel pipe pile structure which has the characteristics of simple construction, strong site adaptability, small disturbance to the construction surrounding environment, high bearing capacity and the like, overcome the defects in the prior miniature pile technology, and improve the economy of the miniature steel pipe pile in a karst area.

The technical scheme for realizing the purpose of the utility model is as follows:

the utility model provides a miniature steel-pipe pile structure of back mud jacking, includes the vertical miniature steel pipe of establishing in the stake hole, the vertical reinforcing bar that sets up to the bottom in stake hole in the miniature steel pipe, the top of miniature steel pipe sets up the bearing plate, and miniature steel pipe inside is filled the grout and is formed cement post to miniature steel pipe top, makes miniature steel pipe, reinforcing bar and bearing plate even as an organic whole, and wherein the outer disc on miniature steel pipe upper portion is filled the grout and is formed special-shaped cement cylinder.

The steel bar is arranged on the central axis in the micro steel pipe.

The special-shaped cement column is a post-grouting body formed by injecting cement paste into soil outside the micro steel pipe on the upper part of the pile hole through a high-pressure pump, and the vertical bearing capacity of the micro steel pipe can be further improved.

The diameter of the miniature steel pipe is slightly smaller than that of the pile hole, and a gap between the miniature steel pipe at the lower part of the special-shaped cement column and the pile hole is filled with cement paste.

The post-grouting miniature steel pipe pile structure provided by the utility model is simple in structure and large in bearing capacity, and can obtain a larger soil area around the pile through the steel pipe and fully exert the side friction resistance of a soil body; an enlarged head can be formed at the pile end by injecting cement slurry into the soil body close to the pile end, so that the bearing capacity of the pile end is improved; and the post-grouting presses the cement grout into the soil body on the upper part of the periphery of the pile near the ground, so that the side frictional resistance of the pile is effectively improved. The method is suitable for the foundation with poor geological type, can fully improve the bearing capacity of the foundation, has the advantages of simple construction, strong site adaptability, small disturbance to the surrounding environment of construction and the like, can effectively reduce the length of the designed pile in the poor geological area, and avoids the uncertainty caused by the poor geological condition as far as possible on the premise of improving the bearing capacity of the foundation.

Drawings

FIG. 1 is a longitudinal sectional view of a post-grouted micro steel pipe pile structure;

in the figure: 1. pile hole 2, miniature steel pipe 3, reinforcing bar 4, special-shaped cement column 5, bearing plate 6 and cement paste.

Detailed Description

The utility model will be further elucidated with reference to the drawings and examples, without however being limited thereto.

Example (b):

as shown in fig. 1, a miniature steel-pipe pile structure of post-grouting, including vertical miniature steel pipe 2 of establishing in stake hole 1, the vertical reinforcing bar 3 that sets up to the bottom in stake hole 1 in miniature steel pipe 2, the top of miniature steel pipe 2 sets up bearing plate 5, the inside grout 6 that fills of miniature steel pipe 2 forms cement post to miniature steel pipe 2 top, makes miniature steel pipe 2, reinforcing bar 3 and bearing plate 5 even as an organic whole, wherein the outer disc on miniature steel pipe 2 upper portion fills the grout and forms special-shaped cement cylinder 4.

The steel bar 3 is arranged on the central axis in the micro steel pipe 2, and a single steel bar with a large diameter can be adopted.

The special-shaped cement column 4 is a post-grouting body formed by injecting cement paste into soil outside the micro steel pipe 2 at the upper part of the pile hole 1 through a high-pressure pump, and can further improve the vertical bearing capacity of the micro steel pipe 2.

The diameter of the micro steel pipe 2 is slightly smaller than that of the pile hole 1, and a gap between the micro steel pipe 2 at the lower part of the special-shaped cement column 4 and the pile hole 1 is filled with cement paste.

A construction method of a post grouting miniature steel pipe pile structure comprises the following steps:

1) after the design depth of the pile hole is reached through the punching of the construction machinery, placing a miniature steel pipe into the pile hole;

2) vertically placing a reinforcing steel bar in the central axis of the micro steel pipe, filling cement slurry into the micro steel pipe, slightly adjusting the position of the micro steel pipe to the designed standard depth, and filling the gap between the lower part of the micro steel pipe and the pile hole with the cement slurry;

3) welding a bearing plate to the top of the miniature steel pipe, and connecting the steel bar, the steel pipe and cement slurry in the steel pipe into a whole by using the bearing plate;

4) and after the cement paste in the micro steel pipe reaches a certain strength, performing post-grouting construction by using a high-pressure pump, and hydraulically pressing the cement paste to a post-grouting body formed in the soil body around the pile outside the steel pipe at the upper part of the micro steel pipe to finish reinforcement.

The bearing capacity of the foundation is improved by the miniature steel pipe pile formed by the method.

In the construction process, the following requirements are required:

1. before the steel pipe is installed, a drilling machine is adjusted according to the positioning of the steel pipe pile, the position of the drilling machine is stable and horizontal, a vertical shaft, a drilling center and a lifting center on the drilling machine are required to be located on the same vertical line, the allowable error of the drilling machine is not more than plus or minus 1 degree, bentonite slurry with high viscosity is selected as circulating liquid for punching, the sand content of the slurry is less than 4 percent, the water loss is less than 15L/30min, the colloid rate is more than 90 percent, a special drill is used for cleaning holes at the bottom of the pile after the punching is finished, processed steel bars and steel pipes are hoisted to the designed depth, and grouting pipes are respectively arranged on the inner side and the outer side of the steel pipe.

2. Grouting is carried out in the steel pipe by adopting a PVC sleeve valve pipe, grout outlet holes are arranged at intervals of 30cm, the diameter of each grout outlet hole is 8mm, cement grout is prepared according to the proportion, and the water-solid ratio is 0.5: and 1, controlling the water consumption by using a flowmeter, stirring for not less than 180s, and after the slurry is filled in the steel pipe pile, finely adjusting the position of the miniature steel pipe to the designed standard depth.

3. And after the grouting is finished and the inspection is qualified, cutting exposed parts of the steel pipe and the steel bar according to requirements, and fixing and sealing by adopting a bearing plate.

4. Preparing cement slurry after the inside of the steel pipe pile has certain strength, cleaning holes of a grouting pipeline, performing post-grouting treatment on a designed soil layer by using a high-pressure grouting pump, determining grouting amount and grouting pressure, controlling the water cement ratio to be 0.4-0.45 and the grouting pressure to be about 0.35MPa, and stopping grouting when the grouting amount reaches a preset design amount or the ground generates grout bleeding.

Claims

1. The utility model provides a miniature steel-pipe pile structure of back mud jacking, its characterized in that, includes the vertical miniature steel pipe of establishing in the stake hole, the vertical reinforcing bar that sets up to the bottom in stake hole in the miniature steel pipe, the top of miniature steel pipe sets up the bearing plate, and miniature steel pipe is inside to be filled the grout and forms cement column to miniature steel pipe top, makes miniature steel pipe, reinforcing bar and bearing plate even as an organic whole, and wherein the outer disc on miniature steel pipe upper portion is filled the grout and is formed special-shaped cement column body.

2. The post-grouting micro steel pipe pile structure according to claim 1, wherein the steel bar is arranged on a central axis in the micro steel pipe.

3. The post-grouting miniature steel pipe pile structure according to claim 1, wherein the special-shaped cement column is a post-grouting body formed by injecting cement slurry into a soil body outside the miniature steel pipe at the upper part of the pile hole through a high-pressure pump, so that the vertical bearing capacity of the miniature steel pipe can be further improved.

4. The structure of a post-grouting micro steel pipe pile according to claim 1, wherein the diameter of the micro steel pipe is slightly smaller than the diameter of the pile hole, and a gap between the micro steel pipe at the lower part of the special-shaped cement column and the pile hole is filled with cement paste.